Based On DdRAD-seq Technology, The Phylogenetic And Gene Introgression Of Hainan Lanxian And Lanshenxian Were Studied

Several Cyornis hainanus populations in Vietnam and Guangdong(China)were recently found to display plumage reminiscent of C.rubeculoides klossi.A previous study using three mtDNA loci(cytb,COI,ND2)and five nuclear loci(BRM,CHDIZ,MUSK,myo and Z185)showed a lack of genetic differentiation between C.hainanus and C.r.klossi.However,given that a limited amount of data,i.e.6Kb from eight mitochondrial and nuclear genetic markers were investigated,fine scale population genomic structure may not have been elucidated.However,these previous results recall the necessarity of revisiting the taxonomic status between C.hainanus and C.r.klossi,and further rendering the possibility of the genetic introgression through hybridization or incomplete lineage sorting.In this study,we used ddRAD-seq approach based on the next generation sequencing to generate a data set of 21,283 genome-wide single nucleotide polymorphisms(SNPs)from 45 individuals,covering six relevant subspecies/populations of C.hainanus,C.rubeculoides,C.glaucicomans,and C.unicolor as outgroup.Phylogenetic and population genomic analyses indicate that the taxa klossi and hainanus are genetically identical.We propose a taxonomic revision,based on the principle of priority,to subsume taxon klossi under C.hainanus.We further recommend that both taxa should be recognized as a single species of C.hainanus because the extent of orange on the breast may be a colour morph that differs across populations.Based on population genomic analyses,a female individual resembling C.hainanus morphologically was found to be from an interbreeding origin with C.glaucicomans.A test for introgression confirms possible ancestral admixture between C.hainanus and C.glaucicomans.Taken together,our results demonstrate evidence of introgression between Cyornis flycatchers and this implies the occurrence of gene flow between species that are not the most closely related congeners,which is an extremely rare occurrence in songbirds.Further studies focusing on exploring the potential hybrid zone(northern and eastern regions of Yunnan)would be required to elucidate the extent of introgression between C.hainanus and C.glaucicomans.